How to Increase Testosterone Naturally: One Thing Works, and It Isn’t a Supplement
One thing works, it is well evidenced, and it is not sold in a tub.
The rest of the standard list — sleep more, lift heavy, take vitamin D — is a mixture of unresolved, misunderstood, and measured-and-found-to-do-nothing. In that order.
| Lever | Effect on testosterone |
| Weight loss — surgery | +208 ng/dL |
| Weight loss — diet | +72 ng/dL |
| Sleep | unresolved — two small studies disagree |
| Resistance training | no change over 12 months |
| Vitamin D | no effect |
The lever that works
In 2024, researchers pooled 44 studies covering 1,774 men to answer one question: how much testosterone do you get back by losing weight? [1]
Losing weight on a low-calorie diet raised total testosterone by about 72 ng/dL. Losing it through bariatric surgery raised it by about 208. Free testosterone moved in the same pattern. Median follow-up was 26 weeks.
An older meta-analysis of 24 studies found almost exactly the same thing — about 83 ng/dL from diet, 252 from surgery, both at p < 0.0001. [2] Two independent teams, a decade apart, different study pools, same answer.
And it is dose-dependent, which is the part that matters if you are not considering surgery. In the older analysis: “Multiple regression analysis shows that the degree of body weight loss is the best determinant of TT rise.” [2] The more you lose, the more you get back. The gain was also larger in younger men, in men who were heavier to begin with, and in men without diabetes.
Why fat lowers testosterone in the first place
Fat tissue is not inert storage. It makes an enzyme called aromatase, which converts testosterone into oestradiol — the main form of oestrogen. More fat means more of that conversion, and the resulting oestradiol signals the brain to dial down the hormones that tell the testes to produce testosterone in the first place.
The meta-analysis found exactly that footprint. Weight loss decreased oestradiol and increased gonadotropins — the pituitary signals that drive testosterone production. [2] The mechanism and the outcome point the same way, which is a large part of why this finding is solid rather than merely repeated.
It is also common enough to matter. Among severely obese men presenting for bariatric surgery, 64% had obesity-associated hypogonadism. [3] Not a rare complication. The majority.
Which reframes part of what we covered in the last piece: the Boston cohort found that gaining four to five BMI points did to a man’s testosterone roughly what a decade of ageing did. This is the same relationship, running the other way. It is one of the few levers in this whole area that goes backwards as readily as it goes forwards.
Sleep: the advice everyone gives, and the evidence nobody checks
You have read that sleep deprivation tanks your testosterone by 10 to 15%. It is one of the most-repeated facts in men’s health.
Here is where it comes from. A 2011 research letter in JAMA put ten men, average age 24, through three nights of ten-hour bedtimes and then eight nights of five-hour bedtimes. Daytime testosterone came out at 16.5 nmol/L after restriction versus 18.4 rested — roughly 476 against 531 ng/dL. [4]
The p-value was .049.
That is a real result, published in a serious journal, and it is also ten men and a p-value that scraped under the line by a thousandth. Neither of those facts travels with the 10-to-15% figure.
So what happened when someone set out to test it properly? In 2019 a team ran two randomised controlled studies. The first restricted 14 men to four hours in bed versus nine, for five nights — more severe than the original. No significant effect on testosterone. The second put 13 men on an hour and a half less sleep a night for six weeks. Testosterone was slightly lower, but rose over time relative to the control condition. [5]
Their conclusion, in full: “Sleep restriction does not adversely affect plasma testosterone levels in healthy young men.” [5]
We are not going to tell you that settles it either, because those studies are also small — 14 men and 13 men. The authors said as much themselves: “Given prior contradicting evidence, confirmatory studies should be done.” [5]
The honest position is unresolved. A famous small study found an effect; the randomised studies designed to check it did not. What you should take from that is not that sleep is unimportant — sleep does a great many measurable things and this page is not about them. It is that the specific, confident number you have been quoted rests on ten people.
Lifting: the spike is real and it is not what you think
Anyone who has trained knows testosterone rises after a heavy session. The inference everyone draws is that training raises your testosterone, and that the rise is why you grow.
A study in 2015 did something unusually careful: it measured not just the level but the production rate and the clearance rate, using stable isotope dilution — tracking a labelled version of the hormone to see how fast the body makes it and how fast it removes it. Men did heavy leg presses before and after twelve months of resistance training. [6]
Two findings. First, the acute post-exercise rise in blood testosterone “appeared to be induced by decreased metabolic clearance rate” — your body was removing it more slowly, not making more of it. [6] The spike is a traffic jam, not extra production.
Second, after a year of training: “No changes were observed in T metabolism due to RT indicating a homeostatic stability for this hormone in men of different ages.” [6]
The honest caveat, and it is a big one: this study had five younger men and eight older ones. Thirteen people. It is a mechanistic study, not a population one, and its value is in what it measured rather than how many it measured it in.
None of which is an argument against lifting. Resistance training builds muscle, and it does so whether or not your testosterone shifts. The point is narrower: if you are lifting in order to move a number on a blood test, the evidence does not support that as the mechanism.
Vitamin D: measured, and it did nothing
This one has a clean answer, which is rare enough to be worth stating plainly.
A randomised, double-blind, placebo-controlled trial gave 98 healthy men 20,000 IU of vitamin D3 a week for twelve weeks, and measured testosterone by mass spectrometry — the accurate method. Result: “no significant treatment effect on TT was found.” The median change was 0.5 nmol/L, p = 0.497. [7]
A meta-analysis of eight trials, with doses ranging from 600 IU a day to 60,000 IU a week and durations from six weeks to three years, agrees: no significant effect on total testosterone (p = 0.336) and none on SHBG (p = 0.204). Subgroup analyses by dose, frequency, duration and baseline vitamin D status found nothing either. [8]
One detail from the trial worth flagging, because it runs opposite to expectation: vitamin D significantly worsened one measure of insulin sensitivity. [7] That is a single secondary outcome in one trial and should not be over-read. It is mentioned here because we would report it if it had gone the other way.
So what about foods?
There is no list. That is the answer to the query, and it is not evasion.
No individual food has been shown in controlled trials to raise testosterone in men who are not deficient in something. What food does is determine your body weight over time, and body weight is the lever that works. The mechanism runs through the scale, not through any particular ingredient.
Which means the honest version of “foods that boost testosterone” is: the ones that leave you carrying less fat a year from now. That is a less satisfying headline and a considerably more useful one.
The verdict
Losing weight raises testosterone. That is Established — 44 studies and 1,774 men in one meta-analysis, 24 studies in another, agreement between them, a dose-response with the amount lost, and a mechanism that shows up in the hormone data as clearly as in the outcome.
Expect roughly 72 ng/dL from losing weight by diet. It is not a transformation, and it is a real, replicated, non-commercial effect that no supplement in this series has come close to matching — ashwagandha managed 57 ng/dL in men, and that is the best-performing supplement we have checked.
Sleep is unresolved and the famous number rests on ten people. Lifting is excellent for reasons that are not this one. Vitamin D does nothing to testosterone, and it has been properly measured doing nothing.
If your reading came back low and you are carrying extra weight, you already know the intervention with the best evidence behind it. It is the one nobody can sell you.
Part 4 of a series on testosterone. Earlier: whether to get tested at all and what a normal level actually is. Next: free versus total testosterone, and whether testosterone boosters do anything.
Related: normal testosterone levels by age · should you get your testosterone tested · ashwagandha benefits · does lack of sleep cause weight gain
